TITLE:   GCN CIRCULAR
NUMBER:  24455
SUBJECT: LIGO/Virgo S190510g: GRAWITA REM optical observations
DATE:    19/05/10 14:42:46 GMT
FROM:    Maria Grazia Bernardini at INAF/Brera  <mgbernardini79@gmail.com>

P. D'Avanzo (INAF-OAB), L. Izzo (IAA), S. Yang (INAF-OAPd), E. Palazzi 
(INAF-OAS), S Campana (INAF-OAB),

S. Benetti (INAF-OAPd), M.G. Bernardini (INAF-OAB), M.T. Botticella 
(INAF-OAC), M. Branchesi (GSSI),

A. Bulgarelli (INAF-OAS), S. Campana (INAF-OAB), E. Cappellaro 
(INAF-OAPd), R. Carini (INAF-OAR), R. Ciolfi (INAF-OAPd),

S. Covino (INAF-OAB), V. D'Elia (ASI-SSDC), M. Della Valle (INAF-OAC), 
  A. Grado (INAF-OAC), G. Greco (Univ. Urbino),

A. Melandri (INAF-OAB), L. Nicastro (INAF-OAS), S. Piranomonte 
(INAF-OAR), A. Rossi (INAF-OAS), V. Testa (INAF-OAR),

L. Tomasella (INAF-OAPd), E. Brocato (INAF-OAAb, INAF-OAR), on behalf of 
GRAWITA report:


We carried out optical follow-up observations of the LIGO/Virgo GW 
trigger S190509g (LVC, GCN Circ. 24442) with the 60-cm

robotic telescope REM located at the La Silla Observatory (Chile). The 
observations started at 2019-05-10 at 05:27:51 UT,

simultaneously in the g, r, i, z bands (the REM NIR camera was not 
operational).


We observed the following galaxies within the 90% probability of the 
initial bayestar skymap visible from La Silla:


RA(J2000) Dec(J2000) Dist(Mpc) Abs_Mag(B)

--------------------------------------------------------------

  14:40:29.9303:14:01.1   400.91 -20.19

  13:40:22.5600:14:12.1   335.74 -19.36

  13:39:26.41-04:38:43.7   331.50 -20.14

  14:40:56.6403:09:10.7   376.70 -19.83

  14:17:12.5701:59:31.5   261.43 -20.30

  13:17:09.12-00:57:28.1   366.44 -19.74

  13:40:11.16-04:36:24.0   351.69 -19.99

  14:55:34.8008:39:43.5   376.70 -19.51

  14:32:03.12-01:10:03.7   243.01 -19.33

  14:31:11.16-02:37:20.2   315.22 -19.81

  14:29:11.5209:38:11.6   385.48 -18.77

  14:17:44.1601:58:52.6   259.42 -20.12

  14:30:39.4007:16:30.0    21.40 -19.47

  14:44:57.6000:50:40.1   317.69 -18.18

  13:53:50.6400:50:43.3   279.25 -19.74


No clear counterpart for S190509g is found down to a typical 3sigma 
magnitude of r > 19 (AB).


We report the presence of a possible transient (likely unrelated to 
S190509g) found in the analysis of the REM

frames at the following coordinates (J2000):

RA = 14:29:15.99

Dec = +09:41:12.3

(+/- 1").


The source has a magnitude of r = 17.3 +/- 0.1 (AB, calibrated against 
the SDSS). We note that this object is

3.5" from the SDSS galaxy SDSS J142916.22+094112.1, whose catalogue 
magnitude is r = 22.56 +/- 0.20 and

photometric redshift is z = 0.182 +/- 0.073.


Further analysis and observations are planned.